Sam Saffron 88249932a0 PERF: remove SQL notifiers for every SQL execution
Benchmarking:

```
Benchmark.ips do |b|
  b.report("simple") do
    User.first
  end
end

ActiveSupport::Notifications.notifier.listeners_for("sql.active_record").clear

Benchmark.ips do |b|
  b.report("simple") do
    User.first
  end
end

```

```
sam@arch discourse % RAILS_ENV=production ruby script/micro_bench.rb

Before

Calculating -------------------------------------
              simple      3.289k (± 4.4%) i/s -     16.575k in   5.049771s
After

Calculating -------------------------------------
              simple      3.491k (± 3.6%) i/s -     17.442k in   5.002226s
````
2019-05-09 17:44:46 +10:00
..
2019-05-08 23:22:51 -07:00
2019-04-01 11:06:47 -04:00
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2019-03-26 18:16:58 +08:00